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膨润土因具有湿胀、干缩特性,其水力-力学性质易受干湿循环的影响。采用饱和盐溶液蒸汽平衡法研究了干湿循环对压实高庙子钙基膨润土持水特性的影响。对相同条件下制作的试样进行0~6次干湿循环,选取其中的原试样(0次)、循环3次和6次试样,进行蒸汽平衡法试验,测定其土-水特征曲线。同时,在0~6次干湿循环过程中,对每一次脱湿后试样表面采集图像,用数字图像处理技术提取了收缩及裂隙开展区域,分析得到收缩率与裂隙率。试验结果表明:随着干湿循环次数的增加(0→3次时),土-水特征曲线向下平移、持水性下降、孔隙比增大、平均骨架应力减小,试样烘干时收缩率和裂隙率增加明显;但随着循环次数的继续增加(3→6次时),持水性、收缩率和裂隙率趋于稳定。
Because of its swelling and shrinkage characteristics, bentonite is susceptible to wet-dry cycling due to its hydraulics and mechanical properties. The effect of drying and wetting cycles on the water holding capacity of compacted Gaogiaozi calcium bentonite was studied by using saturated salt solution vapor balance method. The samples made under the same conditions were subjected to 0 to 6 wet-dry cycles, and the original samples (0 times), 3 times and 6 times of the samples were selected for steam equilibrium test, and the soil-water characteristic curve . At the same time, during the 0 ~ 6 cycles of wetting and drying, images were taken on the surface of each sample after desiccation, and the areas of shrinkage and fracture development were extracted by digital image processing technology. The shrinkage and fracture rate were analyzed. The experimental results show that with the increase of the number of wet and dry cycles (0 → 3 times), the soil-water characteristic curve shifts downward, the water holding capacity decreases, the void ratio increases, the average skeleton stress decreases and the sample shrinks on drying The rate and the crack rate increased obviously. However, with the increase of the number of cycles (3 → 6 times), the water holding capacity, the shrinkage rate and the fracture rate tended to be stable.